The US's slavery finding against Australia should come as no surprise

Donald Trump has been explicit about his plans after the Supreme Court struck down his earlier tariffs. (Reuters: Kevin Lamarque)

The US's proposal to use a tariff to punish Australia over slave labour should come as no surprise.

That's not to say Donald Trump's "America First" priorities have morphed. The US is not reshaping its trade relationships to defend foreign workers' rights.

It is simply doing what it said it would do after the US Supreme Court killed off most of Trump's earlier tariffs in February.

That is, it is finding new reasons to impose tariffs and trying to ensure those reasons can survive the courts.

The trade investigation that made adverse findings against Australia — along with every other country that was investigated — was launched soon after that Supreme Court ruling.

Trump had been using tariffs to increase his power over other countries until the court got involved. If he was angry with a country or its leader, he frequently expressed it with a Truth Social post threatening tariff-related consequences.

The planned new tariff is to be slapped on dozens of countries that have allegedly failed to take action to prevent slavery and forced labour.

Immediately after the court decision, Trump and his trade officials were explicit about their plan to run special trade investigations so they could bring tariffs back.

"Other alternatives will now be used to replace the [tariffs] that the court incorrectly rejected," Trump said at the time. "We have alternatives. Great alternatives."

The so-called "Section 301" investigations, named for the relevant section of trade law, are a legal way to produce justifications for tariffs.

Trump's top trade official, Jamieson Greer, had promised to "fast-track" such investigations, with a focus on eight areas, including forced labour.

"The administration was clear immediately after the Supreme Court ruling that it would be looking for continuity in tariff policy," said trade lawyer Patrick Childress, who worked in the US government's trade office under both Trump and Joe Biden.

"So that's sort of the guiding framework that you should be thinking about when you look at the tariffs that are in place now and what we can expect from tariffs going forward."

But this investigation also produced a less predictable result.

The ruling on tariffs is a hugely consequential decision that has infuriated the president, who is now looking for workarounds.

When Trump unveiled his initial "Liberation Day" tariffs last year, Australia was among the luckiest of the losers.

Its exports were slapped with a t